Outdoor unit for a refrigeration cycle apparatus and refrigerating cycle device

ABSTRACT

An outdoor unit includes at least one heat exchanger, a first motor including a first fan, a second motor including a second fan, an inverter that applies voltage to the first motor and the second for respectively, a connection switching unit that switches the voltage applied to the second motor between on and off, and a control unit that controls the inverter and the connection switching unit. The inverter is disposed closer to the first motor than to the second motor.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of InternationalPatent Application No. PCT/JP2018/020884 filed on May 31, 2018, thedisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an outdoor unit and a refrigerationcycle apparatus including the outdoor unit.

BACKGROUND

A technology for making one inverter drive a plurality of motors isgenerally used. With this technology, even when the load concentrates ona particular motor, current supplied to each motor can be controlledwith ease and each motor can be driven in a stable manner (see PatentReference 1, for example). When this technology is applied to an outdoorunit for a refrigeration cycle apparatus, attaching a fan to each motormakes it possible to control the driving of the fans by use of oneinverter. In other words, air currents generated by the fans can becontrolled with one inverter.

PATENT REFERENCE

Patent Reference 1: Japanese Patent Application Publication No.2001-54299

In an outdoor unit for a refrigeration cycle apparatus, when the drivingof a first fan is continued and the driving of a second fan is stopped,it becomes unlikely that heat from the inverter is discharged by the aircurrent generated by the second fan, and thus There is a problem in thatcooling efficiency of a heat exchanger in the outdoor unit in regard tothe second fan's side drops and heat exchange efficiency of the heatexchanger on the second fan's side drops.

SUMMARY

An object of the present invention, which has been made to resolve theabove-described problem, is to increase the heat exchange efficiency ofa heat exchanger on a second fan's side.

An outdoor unit according to the present invention is an outdoor unitfor a refrigeration cycle apparatus, including:

at least one heat exchanger;

a first motor including a first rotor and a first fan, the first fanrotating together with the first rotor;

a second motor including a second rotor and a second fan, the second fanrotating together with the second rotor;

a first lead wire electrically connected to the first motor;

a second lead wire electrically connected to the second motor;

an inverter that applies voltage to the first motor and the second motorthrough the first lead wire and the second lead wire respectively;

a connection switching unit that is electrically connected to the secondlead wire and switches the voltage applied to the second motor betweenon and off; and

a controller that controls the inverter and the connection switchingunit,

wherein a path through which an air current generated by the first fanpasses extends from a lower side to an upper side in the outdoor unit,

the path extending from the lower side to the upper side in the outdoorunit passes through the inverter and the at least one heat exchanger,and

the inverter is disposed closer to the first motor than to the secondmotor.

According to the present invention, there is no inverter in a secondpath through which an air current generated by the second fan passes,and thus the heat exchange efficiency of the heat exchanger on thesecond fan's side can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a motor driving device according to a firstembodiment of the present invention.

FIG. 2 is a functional block diagram showing the configuration of acontrol unit.

FIG. 3A is a diagram showing an example of a phase estimate value, aleading phase angle and an applied voltage phase.

FIG. 3B is a diagram showing an example of voltage command valuesobtained by a coordinate transformation unit.

FIG. 3C is a diagram showing an example of PWM signals.

FIG. 4 is a Graph showing the relationship between a current leadingangle and magnet torque, the relationship between the current leadingangle and reluctance torque, and the relationship between the currentleading angle and combined torque.

FIG. 5 is a diagram schematically showing internal structure of anoutdoor unit according to a second embodiment.

FIG. 6 is a diagram schematically showing another example of theinternal structure of the outdoor unit.

FIG. 7 is a diagram schematically showing still another example of theinternal structure of the outdoor unit.

FIG. 8 is a diagram showing an example of the flow of air currents inthe outdoor unit when a second motor is stopped.

FIG. 9 is a diagram showing another example of the flow of air currentsin the outdoor unit when a first motor and the second motor are driven.

FIG. 10 is a diagram showing still another example of the internalstructure of the outdoor unit.

FIG. 11 is a diagram showing still another example of the internalstructure of the outdoor unit.

FIG. 12 is a diagram showing the direction of current flowing through afirst lead wire and the direction of current flowing through a secondlead wire in a core.

FIG. 13 is a diagram showing an example of the configuration of arefrigeration cycle apparatus according to a third embodiment.

FIG. 14 is a Mollier diagram in regard to the condition of therefrigerant of a heat pump device shown in FIG. 13.

DETAILED DESCRIPTION First Embodiment

FIG. 1 is a diagram showing a motor driving device 50 according to afirst embodiment of the present invention. This motor driving device 50is a device for driving a first motor 41 and a second motor 42. Thefirst motor 41 and the second motor 42 are permanent magnet synchronousmotors, for example. In this case, the first motor 41 and the secondmotor 42 include permanent magnets; each of a rotor of the first motor41 and a rotor of the second motor 42 includes a permanent magnet.

The motor driving device 50 includes a rectifier 2, a smoothing unit 3,an inverter 4, an inverter current detection unit 5, a motor currentdetection unit 6, an input voltage detection unit 7, a connectionswitching unit 8 and a control unit 10.

The rectifier 2 rectifies AC power from an AC power supply 1 and therebygenerates DC power.

The smoothing unit 3, formed of a capacitor or the like, smoothes the DCpower from the rectifier 2 and supplies the smoothed DC power to theinverter 4.

Incidentally, while the AC power supply 1 is a single-phase power supplyin the example of FIG. 1, the AC power supply may also be a three-phasepower supply. When the AC power supply 1 is a three-phase power supply,a three-phase rectifier is used as the rectifier 2.

While an aluminum electrolytic capacitor having high capacitance isgenerally used as the capacitor of the smoothing unit 3 in many cases, afilm capacitor having a long operating life may also be used. It is alsopossible to configure the smoothing unit 3 to inhibit harmonic currentin the current flowing through the AC power supply 1 by using acapacitor having low capacitance.

Further, a reactor (not shown) may be inserted between the AC powersupply 1 and the smoothing unit 3 in order to inhibit harmonic currentor improve the power factor.

The inverter 4 receives voltage from the smoothing unit 3 as the inputand outputs three-phase AC power whose frequency and voltage value arevariable. The first motor 41 and the second motor 42 are parallellyconnected to the output of the inverter 4.

The connection switching unit 8 is formed of a single open-close unit 9in the example shown in FIG. 1. The open-close unit 9 is capable ofopening and closing the connection between the second motor 42 and theinverter 4, and the number of motors operated at the same time can beswitched by the opening and closing of the open-close unit 9.

The inverter 4 is formed of at least one of a semiconductor switchingelement or a freewheeling diode, for example. As the semiconductorswitching element forming the inverter 4, an IGBT (Insulated GateBipolar Transistor) or a MOSFET (metal Oxide Semiconductor Field EffectTransistor) is used in many cases.

Incidentally, a freewheeling diode (not shown) may be connected inparallel with the semiconductor switching element for the purpose ofinhibiting surge voltage caused by the switching of the semiconductorswitching element.

It is also possible to use a parasitic diode of the semiconductorswitching element as the freewheeling diode. In cases where a MOSFET isused, a function similar to the freewheeling diode can be implemented byswitching the MOSFET to the ON state with the timing of thefreewheeling.

The material forming the semiconductor switching element is not limitedto silicon (Si); silicon carbide (SiC), gallium nitride (GaN), galliumoxide (Ga₂O₃), diamond or the like as a wide band gap semiconductor isusable, and the use of a wide band gap semiconductor makes it possibleto realize low loss and high-speed switching.

Similarly, the material forming the freewheeling diode is not limited tosilicon (Si); silicon carbide (SiC), gallium nitride (GaN), galliumoxide (Ga₂O₃), diamond or the like as a wide band gap semiconductor isusable, and the use of a wide band gap semiconductor makes it possibleto realize low loss and high-speed switching.

As the open-close unit 9, an electromagnetic contactor such as amechanical relay or a contactor may be used instead of the semiconductorswitching element. In short, any type of component may be used as longas the same function is implemented.

While the open-close unit 9 is provided between the second motor 42 andthe inverter 4 in the example shown in FIG. 1, it is also possible toprovide the open-close unit 9 between the first motor 41 and theinverter 4. The connection switching unit 8 may also be configured toinclude two open-close units. In this case, it is possible to provideone open-close unit between the first motor 41 and the inverter 4 andthe other open-close unit between the second motor 42 and the inverter4. When two open-close units are used. The connection switching unit 8is formed of the two open-close units.

While two motors are connected to the inverter 4 in the example shown inFIG. 1, it is also possible to connect three or more motors to theinverter 4. When three or more motors are connected to the inverter 4,an open-close unit similar to the open-close unit 9 may be providedbetween the inverter 4 and each of the motors. It is also possible toprovide an open-close unit similar to the open-close unit 9 only betweenthe inverter 4 and some of the motors. In these cases, the connectionswitching unit 8 is formed of a plurality of open-close units.

The inverter current detection unit 5 detects current flowing into theinverter 4. For example, the inverter current detection unit 5 obtainscurrent I_(u_all), I_(v_all), I_(w_all) in each phase of the inverter 4(inverter current) based on end-to-end voltages V_(Ru), V_(Rv) andV_(Rw) of resistors R_(u), R_(v) and R_(w) respectively connected inseries with three lower arm switching elements of the inverter 4.

The motor current detection unit 6 detects current of the first motor41. The motor current detection unit 6 includes three currenttransformers that respectively detect currents i_(u_m), i_(v_m) andi_(w_m) in the three phases (phase currents).

The input voltage detection unit 7 detects input voltage (DC busvoltage) V_(dc) of the inverter 4.

The control unit 10 outputs a signal for operating the inverter 4 basedon the current values detected by the inverter current detection unit 5,the current values detected by the motor current detection unit 6 andthe voltage value detected by the input voltage detection unit 7.

Incidentally, while the inverter current detection unit 5 in the aboveexample detects the current in each phase of the inverter 4 by usingthree resistors connected in series with the lower arm switchingelements of the inverter 4, the inverter current detection unit 5 mayalso be configured to detect the current in each phase of the inverter 4by using a resistor connected between a common connection point of thelower arm switching elements and a negative-side electrode of thesmoothing unit 3.

Further, the motor driving device 50 may be provided with a motorcurrent detection unit for detecting current of the second motor inaddition to the motor current detection unit 6 for detecting the currentof the first motor 41.

For the detection of the motor current, it is also possible to use aHall element instead of the current transformer or to use aconfiguration for calculating current from end-to-end voltage of aresistor.

Similarly, for the detection of the inverter current, it is alsopossible to use a current transformer, a Hall element or the likeinstead of the configuration for calculating current from end-to-endvoltage of a resistor.

The control unit 10 can be implemented by a processing circuit. Theprocessing circuit may be formed of special-purpose hardware, software,or a combination of hardware and software. In cases where the processingcircuit is formed by software, the control unit 10 is formed of amicrocomputer including a CPU (Central Processing Unit), a DSP (DigitalSignal Processor), or the like. The control unit 10 may include a memoryas a computer-readable record medium in addition to the CPU. In thiscase, the software can be stored in the memory as a program.

FIG. 2 is a functional block diagram showing the configuration of thecontrol unit 10.

The control unit 10 includes an operation command unit 101, asubtraction unit 102, coordinate transformation units 103 and 104, afirst motor speed estimation unit 105, a second motor speed estimationunit 106, integration units 107 and 108, a voltage command generationunit 109, a pulsation compensation control unit 110, a coordinatetransformation unit 111 and a PWM signal generation unit 112.

The operation command unit 101 generates and outputs a revolution speedcommand value ω_(m)* for a motor. The operation command unit 101 alsogenerates and outputs a switching control signal Sw for controlling theconnection switching unit 8.

The subtraction unit 102 obtains phase currents i_(u_sl), i_(v_sl) andi_(w_sl) of the second motor 42 by subtracting the phase currentsi_(u_m), i_(v_m) and i_(w_m) of the first motor 41 from the phasecurrents i_(u_all), i_(v_all) and i_(w_all) of the inverter 4 detectedby the inverter current detection unit 5.

This is calculation utilizing the relationship that the sum of the phasecurrent i_(u_sl), i_(v_sl), i_(w_sl) of the first motor 41 and the phasecurrent i_(u_sl), i_(v_sl), i_(w_sl) of the second motor 42 equals thephase current i_(u_all), i_(v_all), i_(w_all) of the inverter.

The coordinate transformation unit 103 obtains dq-axis currents i_(d_m)and i_(q_m) of the first motor 41 by coordinate-transforming the phasecurrents and i_(u_m), i_(v_m), i_(w_m) of the first motor 41 from astationary three-phase coordinate system into a rotating two-phasecoordinate system by using a phase estimate value (magnetic poleposition estimate value) θ_(m) of the first motor 41 which will bedescribed later.

The coordinate transformation unit 104 obtains dq-axis currents i_(d_sl)and i_(q_sl) of the second motor 42 by coordinate-transforming the phasecurrents i_(u_sl), i_(v_sl) and i_(w_sl) of the second motor 42 from thestationary three-phase coordinate system into the rotating two-phasecoordinate system by using a phase estimate value (magnetic poleposition estimate value) θ_(sl) of the second motor 42 which will bedescribed later.

The first motor speed estimation unit 105 obtains a revolution speedestimate value ω_(m) of the first motor 41 based on the dq-axis currentsi_(d_m) and i_(q_m) and dq-axis voltage command values v_(d)* and v_(q)*which will be described later.

Similarly, the second motor speed estimation unit 106 obtains arevolution speed estimate value ω_(sl) of the second motor 42 based onthe dq-axis currents i_(d_sl) and i_(q_sl) and the dq-axis voltagecommand values v_(d)* and v_(q)* which will be described later.

The integration unit 107 obtains the phase estimate value θ_(m) of thefirst motor 41 by integrating the revolution speed estimate value ω_(m)of the first motor 41.

Similarly, the integration unit 108 obtains the phase estimate valueθ_(sl) of the second motor 42 by integrating the revolution speedestimate value was of the second motor 42.

Incidentally, while the estimation of the revolution speed and the phasecan be carried out by using a method described in Japanese Patent No.4672236, for example, any method may be used as long as the revolutionspeed and the phase can be estimated. It is also possible to employ amethod of directly detecting the revolution speed or the phase.

The voltage command generation unit 109 calculates the dq-axis voltagecommand values v_(d)* and v_(q)* based on the dq-axis currents i_(d_m)and i_(q_m) of the first motor 41, the revolution speed estimate valueω_(m) of the first motor 41, and a pulsation compensation currentcommand value i_(sl)* which will be described later.

The coordinate transformation unit 111 obtains an applied voltage phaseθ_(v) from the phase estimate value θ_(m) of the first motor 41 and thedq-axis voltage command values v_(u)* and v_(q)*, and obtains voltagecommand values v_(u)*, v_(v)* and v_(w)* in the stationary three-phasecoordinate system by coordinate-transforming the dq-axis voltage commandvalues v_(d)* and v_(q)* from the rotating two-phase coordinate systeminto the stationary three-phase coordinate system based on the appliedvoltage phase θ_(v).

The applied voltage phase θ_(v) is obtained by, for example, adding aleading phase angle θ_(f), which is obtained as θ_(f)=tan⁻¹(v_(q)*/v_(d)*) from the dq-axis voltage command values v_(d)* andv_(q)*, to the phase estimate value θ_(m) of the first motor 41.

FIG. 3A is a diagram showing an example of the phase estimate valueθ_(m), the leading phase angle θ_(f) and the applied voltage phaseθ_(v).

FIG. 3B is a diagram showing an example of the voltage command valuesv_(u)*, v_(v)* and v_(w)* obtained by the coordinate transformation unit111.

FIG. 3C is a diagram showing an example of PWM signals UP, VP, UP, UN,VN and UN.

The PWM signal generation unit 112 generates the PWM signals UP, VP, WP,UN, VN and UN shown in FIG. 3C from the input voltage V_(dc) and thevoltage command values v_(u)*, v_(v)* and v_(w)*.

The PWM signals UP, VP, WP, UN, VN and WN are supplied to the inverter 4and used for controlling the switching elements.

The inverter 4 is provided with a non-illustrated drive circuit thatgenerates drive signals for driving the switching elements of the armsbased on the corresponding PWM signals UP, VP, WP, UN, VP and WN.

The control unit 10 controls the switching elements of the inverter 4between on and off according to the aforementioned PWM signals UP, VP,WP, UN, VN and WN and thereby niches the inverter 4 output AC voltagewhose frequency and voltage value are variable. Accordingly, the controlunit 10 is capable of controlling the inverter 4 so that the AC voltageis applied to the first motor 41 and the second motor 42.

While the voltage command values v_(u)*, v_(v)* and v_(w)* are sinewaves in the example shown in FIG. 3B, the voltage command values mayalso be waves having a third-order harmonic superimposed thereon; wavesof any waveform may be used as long as the driving of the first motor 41and the second motor 42 is possible.

If the voltage command generation unit 109 is configured to generate thevoltage command based exclusively on the dq-axis currents i_(d_m) andi_(q_m) and the revolution speed estimate value ω_(m) of the first motor41, the first motor 41 is controlled appropriately, whereas the secondmotor 42 just operates according to the voltage command values generatedfor the first motor 41 and thus is in a state of not being directlycontrolled.

Therefore, the first motor 41 and the second motor 42 operate in a statewith errors in the phase estimate value θ_(m) and the phase estimatevalue θ_(sl) and the errors become significant especially in a low speedrange.

Upon the occurrence of the errors, current pulsation of the second motor42 occurs and there is the danger of the step-out of the second motor 42and an increase in the loss due to heating by overcurrent. Further,there is a danger that circuit breaking is carried out in response tothe overcurrent, the motor is stopped, and the driving of the loadbecomes impossible.

The pulsation compensation control unit 110, which is provided in orderto resolve such problems, outputs the pulsation compensation currentcommand value i_(sl)*, for inhibiting the current pulsation of thesecond motor 42, by using the q-axis current i_(q_sl) of the secondmotor 42, the phase estimate value θ_(m) of the first motor 41 and thephase estimate value θ_(sl) of the second motor 42.

The pulsation compensation current command value i_(sl)* is determinedbased on the result of a judgment on phase relationship between thefirst motor 41 and the second motor 42 made from the phase estimatevalue θ_(m) of the first motor 41 and the phase estimate value θ_(sl) ofthe second motor 42 so as to inhibit pulsation of the q-axis currenti_(q_sl) that corresponds to torque current of the second motor 42.

The voltage command Generation unit 109 obtains a q-axis current commandvalue θ_(q_m)* for the first motor 41 by performing aproportional-integral operation on the deviation between the revolutionspeed command value ω_(m)* for the first motor 41 from the operationcommand unit 101 and the revolution speed estimate value ω_(m) of thefirst motor 41.

On the other hand, the d-axis current of the first motor 41 is anexcitation current component, and changing its value makes it possibleto control the current phase and to drive the first motor 41 byflux-strengthening control or flux-weakening control. By using thisproperty and incorporating the aforementioned pulsation compensationcurrent command value i_(sl)* into a d-axis current command valueI_(d_m)* for the first motor 41, it is possible to control the currentphase and thereby reduce the pulsation.

The voltage command generation unit 109 obtains the dq-axis voltagecommand values v_(d)* and v_(q)* based on the dq-axis current commandvalues I_(d_m)* and I_(q_m)* obtained as above and the dq-axis currentsi_(d_m) and i_(q_m) obtained by the coordinate transformation unit 103.Namely, the d-axis voltage command value v_(d)* is obtained byperforming the proportional-integral operation on the deviation betweenthe d-axis current command value I_(d_m)* and the d-axis currentI_(d_m), and the q-axis voltage command value v_(q)* is obtained byperforming the proportional-integral operation on the deviation betweenthe q-axis current command value I_(q_m)* and the q-axis currentI_(q_m).

Incidentally, any configuration may be employed for the voltage commandgeneration unit 109 and the pulsation compensation control unit 110 aslong as the same functions can be implemented.

Performing the control described above makes it possible to drive thefirst motor 41 and the second motor 42 with one inverter 4 so that nopulsation occurs to the second motor 42.

Next, a problem in cases where the first motor 41 and the second motor42 are embedded magnet synchronous motors will be described below.

FIG. 4 is a graph showing the relationship between a current leadingangle β and magnet torque, the relationship between the current leadingangle β and reluctance torque, and the relationship between the currentleading angle β and combined torque.

An embedded magnet synchronous motor generates the reluctance torque dueto the difference between d-axis inductance and q-axis inductance inaddition to the magnet torque due to the magnets. The relationshipbetween the current leading angle β and the magnet torque or thereluctance torque is as shown in FIG. 4, for example, and the combinedtorque hits the maximum at a certain current leading angle β between 0[deg] and 90 [deg].

Here, the current leading angle β is a phase angle of the current in thedirection of back electromotive force, that is, with reference to a +qaxis, and in the range from 0 [deg] to 90 [deg], the current leadingangle β increases with the increase in the absolute value of the d-axiscurrent if the q-axis current is constant.

In cases of surface magnet synchronous motors, only the magnet torque isgenerated, and thus the combined torque hits the maximum when thecurrent leading angle β is 0 [deg].

Second Embodiment

FIG. 5 is a diagram schematically showing internal structure of anoutdoor unit 100 according to a second embodiment.

The outdoor unit 100 is an outdoor unit for a refrigeration cycleapparatus. For example, the outdoor unit 100 is used together with anindoor unit in the refrigeration cycle apparatus. The outdoor unit 100may include the motor driving device 50 described in the firstembodiment. With this configuration, the outdoor unit 100 can obtain theadvantages of the motor driving device 50 described in the firstembodiment. In the outdoor unit 100 shown in FIG. 5, the first motor 41,the second motor 42, the inverter 4, the connection switching unit 8 andthe control unit 10 are indicated among the components of the motordriving device 50 according to the first embodiment.

The outdoor unit 100 includes the first motor 41, the second motor 42,at least one heat exchanger (e.g., heat exchangers 43 a and 43 b), afirst lead wire 44 a, a second lead wire 44 b, the inverter 4, theconnection switching unit 8, the control unit 10, and a housing 45covering these components.

The outdoor unit 100 further includes a substrate 46 and a partitionplate 47. The inverter 4, the connection switching unit 8 and thecontrol unit 10 are attached to the substrate 46.

FIG. 6 is a diagram schematically showing another example of theinternal structure of the outdoor unit 100.

As show in FIG. 6, the outdoor unit 100 may also be configured toinclude no partition plate 47.

In this embodiment, the housing 45 is divided into a first housing 45 aand a second housing 45 b. The first housing 45 a and the second housing45 b may either be separated from each other or integrated with eachother.

The first housing 45 a covers the first motor 41, the heat exchanger 43a and the inverter 4. In the example shown in FIG. 5, the first housing45 a covers the substrate 46. Thus, in the example shown in FIG. 5, thefirst housing 45 a also covers the connection switching unit 8 and thecontrol unit 10.

The second housing 45 b covers the second motor 42 and the heatexchanger 43 b.

The housing 45 has at least one first intake port 451 a, at least onesecond intake port 451 b, at least one first discharge port 452 a and atleast one second discharge port 452 b.

In this embodiment, the first housing 45 a has at least one first intakeport 451 a and at least one first discharge port 452 a, and the secondhousing 45 b has at least one second intake port 451 h and at least onesecond discharge port 452 b.

In cases where the housing 45 is separated into the first housing 45 aand the second housing 45 b, a unit including the first motor 41 isreferred to as a first unit 141 and a unit including the second motor 42is referred to as a second unit 142.

In the example shown in FIG. 5, the first unit 141 includes the firsthousing 45 a, the first motor 41, the heat exchanger 43 a, the firstlead wire 44 a, the inverter 4, the connection switching unit 8 and thecontrol unit 10, and the second unit 142 includes the second housing 45b, the second motor 42 and the heat exchanger 43 b.

In cases where the outdoor unit 100 is separated into the first unit 141and the second unit 142, the partition plate 47 is the boundary betweenthe first unit 141 and the second unit 142. However, the partition plate47 may also be provided as a component of the first unit 141 or acomponent of the second unit 142. As shown in FIG. 6, the outdoor unit100 may also be configured not to include the partition plate 47.

The first motor 41 includes a first fan 41 a and a first rotor 41 b.Further, the first motor 41 includes a shaft fixed to the first rotor 41b, and the shaft is fixed also to the first fan 41 a. The first rotor 41b includes a permanent magnet. When the first motor is driven, the firstfan 41 a rotates together with the first rotor 41 b. Accordingly, thefirst fan 41 a generates an air current (namely, air current A1 whichwill be described later).

The second motor 42 includes a second fan 42 a and a second rotor 42 b.Further, the second motor 42 includes a shaft fixed to the second rotor42 b, and the shaft is fixed also to the second fan 42 a. The secondrotor 42 b includes a permanent magnet. When the second motor 42 isdriven, the second fan 42 a rotates together with the second rotor 42 b.Accordingly, the second fan 42 a generates an air current (namely, aircurrent A2 which will be described later).

The first lead wire 44 a is electrically connected to the first motor 41and the inverter 4. The second lead wire 44 b is electrically connectedto the second motor 42 and the connection switching unit 8.Specifically, as shown in FIG. 5, a hole 47 a is formed through thepartition plate 47, and the second lead wire 44 b is connected to thesecond motor 42 and the connection switching unit 8 through the hole 47a. While the first lead wire 44 a is shorter than the second lead wire44 b in the example shown in FIG. 5, the length of the first lead wire44 a may also be the same as that of the second lead wire 44 b.

The connection switching unit 8 is electrically connected to the secondlead wire 44 b, the inverter 4 and the control unit 10. Specifically,the connection switching unit 8 is disposed between the inverter 4 andthe second motor 42. The connection switching unit 8 switches thevoltage applied from the inverter 4 to the second motor 42 between onand off according to a command from the control unit 10. The connectionswitching unit 8 is formed of a wide band gap semiconductor, forexample. This makes it possible to realize low loss and high-speedswitching.

The connection switching unit 8 may also be formed of an electromagneticcontactor. Also in this case, low loss and high-speed switching can berealized.

FIG. 7 is a diagram schematically showing still another example of theinternal structure of the outdoor unit 100.

The “at least one heat exchanger” in the outdoor unit 100 may either beone heat exchanger or two or more heat exchangers. When the outdoor unit100 includes one heat exchanger, the heat exchangers 43 a and 43 b areintegrated with each other as shown in FIG. 7. In this case, the heatexchanger 43 a is on the first fan 41 a's side of the heat exchanger andthe heat exchanger 43 b is on the second fan 42 a's side of the heatexchanger. The first fan 41 a's side of the heat exchanger will bereferred to also as “the first unit 141's side of the heat exchanger” or“the first side of the heat exchanger”, and the second fan 42 a's sideof the heat exchanger will be referred to also as “the second unit 142'sside of the heat exchanger” or “the second side of the heat exchanger”.

The at least one heat exchanger performs heat exchange with arefrigerant. In this embodiment, the heat exchanger 43 a performs theheat exchange with the refrigerant and the heat exchanger 43 b alsoperforms the heat exchange with the refrigerant.

The inverter 4 is capable of driving a plurality of motors as mentionedabove. In this embodiment, the inverter 4 is capable of applying voltageto the first motor 41 and the second motor 42 through the first leadwire 44 a and the second lead wire 44 b respectively. In other words,the inverter 4 is capable of driving the first motor 41 and the secondmotor 42. However, in cases where the outdoor unit 100 includes three ormore motors, the inverter 4 is capable of driving the three or moremotors.

The inverter 4 is disposed closer to the first motor 41 than to thesecond motor 42. The arrangement of the inverter 4 is not limited tothat in this embodiment as long as the inverter 4 is situated closer tothe first motor 41 than to the second motor 42.

As described above, the control unit 10 controls the inverter 4 and theconnection switching unit 8. The control unit 10 is disposed closer tothe first motor 41 than to the second motor 42.

In the outdoor unit 100, a device including the inverter 4 and thecontrol unit 10 will be referred to also as a “motor control device”. Inthis embodiment, the motor control device is disposed closer to thefirst motor 41 than to the second motor 42.

In this embodiment, the substrate 46 is disposed closer to the firstmotor 41 than to the second motor 42. Thus, the connection switchingunit 8 is also disposed closer to the first motor 41 than to the secondmotor 42.

FIG. 8 is a diagram showing an example of the flow of air currents inthe outdoor unit 100 when the second motor 42 is stopped.

When the refrigeration cycle apparatus lowers its air-conditioningcapacity, a motor among the plurality of motors that is driven by thecontrol unit 10 is referred to as a master motor or a main motor, and amotor stopped by the control unit 10 is referred to as a slave motor ora subsidiary motor.

In this embodiment, when the refrigeration cycle apparatus lowers itsair-conditioning capacity, one of the first motor 41 and the secondmotor 42 stops. In the example shown in FIG. 8, when the refrigerationcycle apparatus lowers its air-conditioning capacity, the first motor 41is driven and the driving of the second motor 42 stops. In this case,the control unit 10 controls the inverter 4 and the connection switchingunit 8 and thereby make them drive the first motor 41 and stop thesecond motor 42. Accordingly, the second fan 42 a stops.

While the first motor 41 is driven, the first fan 41 a rotates and anair current A1 occurs in the first unit 141. Specifically, air currentsinto the first unit 141 through the first intake port 451 a and isdischarged through the first discharge port 452 a to the outside of theoutdoor unit 100 (specifically, the first unit 141).

The path through which the air current A1 passes is a first path P1. Inthe example shown in FIG. 8, the air current A1 flows in the first unit141 from a lower side to an upper side. Thus, the first path P1 extendsfrom the lower side to the upper side in the first unit 141 in theexample shown in FIG. 8. In other words, the first path P1 passesthrough the inverter 4 and the heat exchanger 43 a. It is desirable thatthe first path P1 pass through the control unit 10 in addition to theinverter 4 and the heat exchanger 43 a.

The air current A1 passes the inverter 4 and the heat exchanger 43 a.Accordingly, the inverter 4 and the heat exchanger 43 a are cooled down.

FIG. 9 is a diagram showing another example of the flow of air currentsin the outdoor unit 100 when the first motor 41 and the second motor 42are driven.

In the example shown in FIG. 9, the first motor 41 and the second motor42 are driven. For example, when the refrigeration cycle apparatus ismaintained at a regular air-conditioning capacity or theair-conditioning capacity of the refrigeration cycle apparatus israised, the control unit 10 controls the inverter 4 and the connectionswitching unit 8 and thereby makes them drive the first motor 41 and thesecond motor 42.

While the first motor 41 is driven, the first fan 41 a rotates and theair current A1 occurs in the first unit 141. Specifically, air currentsinto the first unit 141 through the first intake port 451 a and isdischarged through the first discharge port 452 a to the outside of theoutdoor unit 100 (specifically, the first unit 141).

Similarly, while the second motor 42 is driven, the second fan 42 arotates and an air current A2 occurs in the second unit 142.Specifically, air currents into the second unit 142 through the secondintake port 451 b and is discharged through the second discharge port452 b to the outside of the outdoor unit 100 (specifically, the secondunit 142).

The path through which the air current A2 passes is a second path P2. Inthe example shown in FIG. 9, the air current A2 flows in the second unit142 from a lower side to an upper side. Thus, the second path P2 extendsfrom the lower side to the upper side in the second unit 142 in theexample shown in FIG. 9.

The air current A1 passes the inverter 4 and the heat exchanger 43 a.Accordingly, the inverter 4 and the heat exchanger 43 a are cooled down.The air current A2 passes the heat exchanger 43 b. Accordingly, the heatexchanger 43 b is cooled down.

Suppose that the inverter 4 and the control unit 10 are situated in thesecond path P2, heat from the substrate 46, especially heat from theinverter 4 and the control unit 10, is discharged to the inside of thesecond unit 142. If the second motor 42 stops in this state, the heat inthe second unit 142 is unlikely to be discharged to the outside of theoutdoor unit 100 (specifically, the second unit 142). Accordingly,cooling efficiency for the second unit 142's side of the heat exchanger(the heat exchanger 43 b in this embodiment) drops and heat exchangeefficiency on the second unit 142's side of the heat exchanger (the heatexchanger 43 b in this embodiment) drops.

In contrast, in this embodiment, the inverter 4 is disposed closer tothe first motor 41 than to the second motor 42. Specifically, theinverter 4 is situated in the first path P1, whereas the second path P2includes no inverter 4. In this case, the heat from the inverter 4 isdischarged mainly to the inside of the first unit 141, and thus thesecond unit 142's side of the heat exchanger (the heat exchanger 43 b inthis embodiment) is hardly influenced by the heat from the inverter 4.Therefore, even when the second motor 42 is stopped, the drop in theheat exchange efficiency on the second unit 142's side of the heatexchanger (the heat exchanger 43 b in this embodiment) can be prevented.Consequently, the heat exchange efficiency on the second unit 142's sideof the heat exchanger (the heat exchanger 43 b in this embodiment) canbe increased compared to the conventional technology.

Further, in this embodiment, the control unit 10 is disposed closer tothe first motor 41 than to the second motor 42. Specifically, thecontrol unit 10 is situated in the first path P1, whereas the secondpath 52 includes no control unit 10. In this case, the air current A1passes the control unit 10 and the heat exchanger 43 a. Heat from thecontrol unit 10 is discharged mainly to the inside of the first unit141, and thus the second unit 142's side of the heat exchanger (the heatexchanger 43 b in this embodiment) is hardly influenced by the heat fromthe control unit 10. Therefore, even when the second motor 42 isstopped, the drop in the heat exchange efficiency on the second unit142's side of the heat exchanger (the heat exchanger 43 b in thisembodiment) can be prevented. Consequently, the heat exchange efficiencyon the second unit 142's side of the heat exchanger (the heat exchanger43 b in this embodiment) can be increased compared to the conventionaltechnology.

Furthermore, it is desirable that the substrate 46 be disposed closer tothe first motor 41 than to the second motor 42 as in this embodiment. Inthis case, the air current A1 passes the substrate 46 and the heatexchanger 43 a. Heat from the substrate 46 is discharged mainly to theinside of the first unit 141, and thus the second unit 142's side of theheat exchanger (the heat exchanger 43 b in this embodiment) is hardlyinfluenced by the heat from the substrate 46. Therefore, even when thesecond motor 42 is stopped, the drop in the heat exchange efficiency onthe second unit 142's side of the heat exchanger (the heat exchanger 43b in this embodiment) can be prevented. Consequently, the heat exchangeefficiency on the second unit 142's side of the heat exchanger (the heatexchanger 43 b in this embodiment) can be increased compared to theconventional technology. By disposing the substrate 46 not in the secondunit 142 but in the first unit 141 as in this embodiment, the heatexchange efficiency on the second unit 142's side of the heat exchanger(the heat exchanger 43 b in this embodiment) can be increased further.

As described above, in the outdoor unit 100 according to thisembodiment, even when the second motor 42 is stopped, the cooling of theinside of tee outdoor unit 100 can be carried out efficiently, andconsequently, the heat exchange efficiency of the heat exchanger,especially on the second unit 142's side of the heat exchanger (the heatexchanger 43 b in this embodiment), can be increased.

Next, the structure of the first lead wire 44 a and the structure of thesecond lead wire 44 b will be described below.

FIG. 10 is a diagram showing still another example of the internalstructure of the outdoor unit 100.

As described above, the inverter 4 is disposed closer to the first motor41 than to the second motor 42. This configuration allows the length ofthe first lead wire 44 a to be less than that of the second lead wire 44b. However, when the length of the first lead wire 44 a and the lengthof the second lead wire 44 b differ from each other, noise currentpassing through the first lead wire 44 a can be superimposed on signalcurrent passing through the second lead wire 44 b. In this case, thesignal current flowing through the second lead wire 44 b is influencedby noise from the first lead wire 44 a. Similarly, when the length ofthe first lead wire 44 a and the length of the second lead wire 44 bdiffer from each other, noise current passing through the second leadwire 44 b can be superimposed on signal current passing through thefirst lead wire 44 a. In this case, the signal current flowing throughthe first lead wire 44 a is influenced by noise from the second leadwire 44 b.

In the example shown in FIG. 10, the outdoor unit 100 includes a core 48that reduces the noise current. The core 48 is a ferrite core, forexample. The core 48 is referred to also as a noise filter.

In the example shown in FIG. 10, the core 48 is attached to the secondlead wire 44 b. Thus, the core 48 reduces the noise current flowingthrough the second lead wire 44 b. With this configuration, the noisefrom the second lead wire 44 b can be reduced even when the first leadwire 44 a is shorter than the second lead wire 44 b. It is also possibleto at the core 48 to the first lead wire 44 a. In this case, the noisefrom the first lead wire 44 a can be reduced. Accordingly, appropriatecontrol of the first motor 41 and the second motor 42 becomes possible.

FIG. 11 is a diagram showing still another example of the internalstructure of the outdoor unit 100.

FIG. 12 is a diagram showing the direction of current I1 flowing throughthe first lead wire 44 a and the direction of current I2 flowing throughthe second lead wire 44 b in the core 48.

In the example shown in FIG. 11, the length of the first lead wire 44 ais the same as that of the second lead wire 44 b, and the current(specifically, signal current) flowing through the first lead wire 44 ais in sync with the current (specifically, signal current) flowingthrough the second lead wire 44 b. For example, the same current issupplied from the inverter 4 to the first lead wire 44 a and the secondlead wire 44 b. Namely, the first motor 41 and the second motor 42perform synchronized operation. In this case, the signal current flowingthrough the first lead wire 44 a can be influenced by the noise from thesecond lead wire 44 b, and the signal current flowing through the secondlead wire 44 b can be influenced by the noise from the first lead wire44 a.

Therefore, in the example shown in FIG. 11, the outdoor unit 100includes the core 48 for reducing the noise current. The core 48 isattached to the first lead wire 44 a and the second lead wire 44 b.Specifically, as shown in FIG. 12, the core 48 is attached to the firstlead wire 44 a and the second lead wire 44 b so that the current I1flowing through the first lead wire 44 a and the current I2 flowingthrough the second lead wire 44 b are in directions opposite to eachother in the core 48. The current I1 includes the signal current and thenoise current. Similarly, the current I2 includes the signal current andthe noise current.

In the core 48, the current I1 and the current I2 are in directionsopposite to each other and the current (specifically, signal current)flowing through the first lead wire 44 a is in sync with the current(specifically, signal current) flowing through the second lead wire 44b, and thus magnetic flux generated by the current I1 and magnetic fluxgenerated by the current I2 cancel each other. Accordingly, the noisefrom the first lead wire 44 a and the noise from the second lead wire 44b cancel each other. Consequently, the influence of the noise in thefirst lead wire 44 a and the second lead wire 44 b can be reduced. Thisenables appropriate control of the first motor 41 and the second motor42.

Third Embodiment

A refrigeration cycle apparatus 800 according to a third embodiment willbe described below. The refrigeration cycle apparatus 800 is referred toalso as a refrigeration cycle application apparatus.

FIG. 13 is a diagram showing an example of the configuration of therefrigeration cycle apparatus 800 according to the third embodiment.

The refrigeration cycle apparatus 800 includes a heat pump device 900.In this embodiment, some components of the heat pump device 900 form anoutdoor unit 800 a of the refrigeration cycle apparatus 800. Therefrigeration cycle apparatus 800 includes an indoor unit (not shown) inaddition to the outdoor unit 800 a.

The outdoor unit 100 described in the second embodiment can be employedas the outdoor unit 800. This allows the refrigeration cycle apparatus800 to obtain the advantages of the outdoor unit 100 described in thesecond embodiment. In the example shown in FIG. 13, a heat exchanger 907corresponds to the heat exchangers 43 a and 43 b of the outdoor unit 100according to the second embodiment, and fans 910 a and 910 b correspondto the first fan 41 a and the second fan 42 a of the outdoor unit 100according to the second embodiment.

FIG. 14 is a Mollier diagram in regard to the condition of therefrigerant of the heat pump device 900 shown in FIG. 13. In FIG. 14,the horizontal axis represents specific enthalpy and the vertical axisrepresents refrigerant pressure.

An example of the circuit configuration of the heat pump device 900will, be described below.

The heat pump device 900 includes a main refrigerant circuit 908 inwhich a compressor 901, a heat exchanger 902, an expansion mechanism903, a receiver 904, an internal heat exchanger 905, an expansionmechanism 906 and the heat exchanger 907 are successively connectedtogether by piping and the refrigerant circulates. Incidentally, in themain refrigerant circuit 908, a four-way valve 909 is provided on adischarging side of the compressor 901 so that the circulating directionof the refrigerant can be switched.

The outdoor unit 800 a of the refrigeration cycle apparatus 800 includesthe compressor 901, the expansion mechanism 903, the receiver 904, theinternal heat exchanger 905, the expansion mechanism 906, the heatexchanger 907, the four-way valve 909, an expansion mechanism 911, thefan 910 a and the fan 910 b of the heat pump device 900. However, theconfiguration of the outdoor unit 800 a is not limited to that in thisembodiment.

The heat exchanger 907 includes a first part 907 a and a second part 907b, non-illustrated valves are connected to them, and the flow of therefrigerant is controlled depending on the load on the heat pump device900. For example, the refrigerant is fed to both of the first part 907 aand the second part 907 b when the load on the heat pump device 900 isrelatively high, and the refrigerant is fed only to one of the firstpart 907 a and the second part 907 b, e.g., only to the first part 907a, when the load on the heat pump device 900 is relatively low.

The first part 907 a and the second part 907 b are respectively providedwith their corresponding fans 910 a and 910 b placed in the vicinitythereof. The fans 910 a and 910 b are respectively driven by drivingforce of separate motors. For example, the fan 910 a is the first fan 41a of the first motor 41 described in the first or second embodiment, andthe fan 910 b is the second fan 42 a of the second motor 42 described inthe first or second embodiment.

Further, the heat pump device 900 includes an injection circuit 912 thatconnects a connection point between the receiver 904 and the internalheat exchanger 905 and an injection pipe of the compressor 901 by usingpiping. The expansion mechanism 911 and the internal heat exchanger 905are connected to the injection circuit 912 in sequence.

A water circuit 913 in which water circulates is connected to the heatexchanger 902. Incidentally, a device that uses water, such as ahot-water supply system, a radiator or a floor heating system, isconnected to the water circuit 913.

First, the operation of the heat pump device 900 in a heating operationwill be described below in the heating operation, the four-way valve 909is set in the direction of the solid lines. Incidentally, this heatingoperation includes not only the heating used for the air conditioningbut also heating of water for the hot-water supply.

Gas-phase refrigerant that reached high temperature and high pressure(point 1 in FIG. 14) in the compressor 901 is discharged from thecompressor 901 and is liquefied (point 2 in FIG. 14) by heat exchange bythe heat exchanger 902 functioning as a condenser and a radiator. Atthat time, by the heat radiated from the refrigerant, the watercirculating in the water circuit 913 is heated up, and the heated wateris used for the heating, the hot-water supply or the like.

The liquid-phase refrigerant after the liquefaction by the heatexchanger 902 is decompressed by the expansion mechanism 903 and shiftsto a gas-liquid two-phase state (point 3 in FIG. 14). The refrigerantafter shifting to the gas-liquid two-phase state in the expansionmechanism 903 undergoes heat exchange by the receiver 904 withrefrigerant being taken into the compressor 901, and is thereby cooleddown and liquefied (point 4 in FIG. 14). The liquid-phase refrigerantafter the liquefaction by the receiver 904 branches and flows into themain refrigerant circuit 908 and the injection circuit 912.

The liquid-phase refrigerant flowing in the main refrigerant circuit 908undergoes heat exchange by the internal heat exchanger 905 withrefrigerant decompressed by the expansion mechanism 911 into thegas-liquid two-phase state and flowing in the injection circuit 912, andis thereby cooled down further (point 5 in FIG. 14). The liquid-phaserefrigerant after being cooled down by the internal heat exchanger 905is decompressed by the expansion mechanism 906 and shifts to thegas-liquid two-phase state (point 6 in FIG. 14). The refrigerant aftershifting to the gas-liquid two-phase state in the expansion mechanism906 undergoes heat exchange by the heat exchanger 907 as an evaporatorwith outside air and is thereby heated up (point 7 in FIG. 14). Then,the refrigerant after being heated up by the heat exchanger 907 isheated further (point 8 in FIG. 14) by the receiver 904 and is takeninto the compressor 901.

Meanwhile, the refrigerant flowing in the injection circuit 912 isdecompressed by the expansion mechanism 911 (point 9 in FIG. 14) andundergoes heat exchange by the internal heat exchanger 905 (point 10 inFIG. 14) as mentioned above. The refrigerant in the gas-liquid two-phasestate after the heat exchange by the internal heat exchanger 905(injection refrigerant) flows into the compressor 901 through theinjection pipe of the compressor 901 while remaining in the gas-liquidtwo-phase state.

In the compressor 901, the refrigerant taken in from the mainrefrigerant circuit 908 (point 8 in FIG. 14) is compressed and heated tointermediate pressure (point 11 in FIG. 14). The refrigerant compressedand heated to the intermediate pressure (point 11 in FIG. 14) mergeswith the injection refrigerant (point 10 in FIG. 14) and drops intemperature (point 12 in FIG. 14). Then, the refrigerant after thetemperature drop (point 12 in FIG. 14) is further compressed and heatedinto high temperature and high pressure and is discharged (point 1 inFIG. 14).

Incidentally, when the injection operation is not performed, the degreeof opening of the expansion mechanism 911 is set to be fully closed.Specifically, while the degree of opening of the expansion mechanism 911is larger than a certain value when the injection operation isperformed, the degree of opening of the expansion mechanism 911 is setless than the certain value when the injection operation is notperformed. This prevents the refrigerant from flowing into the injectionpipe of the compressor 901. The degree of opening of the expansionmechanism 911 is electronically controlled by a control unit formed of amicrocomputer or the like.

Next, the operation of the heat pump device 900 in a cooling operationwill be described below. In the cooling operation, the four-way valve909 is set in the direction of the broken lines. Incidentally, thiscooling operation includes not only the cooling used for the airconditioning but also cooling of water, refrigeration of food, and soon.

Gas-phase refrigerant that reached high temperature and high pressure(point 1 in FIG. 14) in the compressor 901 is discharged from thecompressor 901 and is liquefied (point 2 in FIG. 14) by heat exchange bythe heat exchanger 907 functioning as a condenser and a radiator. Theliquid-phase refrigerant after the liquefaction by the heat exchanger907 is decompressed by the expansion mechanism 906 and shifts to thegas-liquid two-phase state (Point 3 in FIG. 14). The refrigerant aftershifting to the gas-liquid two-phase state in the expansion mechanism906 undergoes heat exchange by the internal heat exchanger 905 and isthereby cooled down and liquefied (point 4 in FIG. 14). In the internalheat exchanger 905, the heat exchange is performed between therefrigerant after shifting to the gas-liquid two-phase state in theexpansion mechanism 906 and the refrigerant after the liquefaction bythe internal heat exchanger 905 into liquid-phase refrigerant anddecompression by the expansion mechanism 911 into the gas-liquidtwo-phase state (point 9 in FIG. 14). The liquid-phase refrigerant afterundergoing the heat exchange by the internal heat exchanger 905 (point 4in FIG. 14) branches and flows into the main refrigerant circuit 908 andthe injection circuit 912.

The liquid-phase refrigerant flowing in the main refrigerant circuit 908undergoes heat exchange by the receiver 904 with the refrigerant beingtaken into the compressor 901 and is thereby cooled down further (point5 in FIG. 14). The liquid-phase refrigerant cooled down by the receiver904 is decompressed by the expansion mechanism 903 and shifts to thegas-liquid two-phase state (point 6 in FIG. 14). The refrigerant aftershifting to the gas-liquid two-phase state in the expansion mechanism903 undergoes heat exchange by the heat exchanger 902 as an evaporatorand is thereby heated up (point 7 in FIG. 14). At that time, by theabsorption of heat by the refrigerant, the water circulating in thewater circuit 913 is cooled down and is used for the cooling,refrigeration, freezing or the like. Then, the refrigerant heated up inthe heat exchanger 902 is heated further by the receiver 904 (point 8 inFIG. 14) and is taken into the compressor 901.

Meanwhile, the refrigerant flowing in the injection circuit 912 isdecompressed by the expansion mechanism 911 (point 9 in FIG. 14) andundergoes heat exchange by the internal heat exchanger 905 (point 10 inFIG. 14) as mentioned above. The refrigerant in the gas-liquid two-phasestate (injection refrigerant) after the heat exchange by the internalheat exchanger 905 flows into the compressor 901 through the injectionpipe of the compressor 901 while remaining in the gas-liquid two-phasestate.

The compression operation in the compressor 901 is the same as that inthe heating operation.

Incidentally, when the injection operation is not performed, the degreeof opening of the expansion mechanism 911 is set to be fully closed inthe same way as in the heating operation so as to prevent therefrigerant from flowing into the injection pipe of the compressor 901.

In the above example, the heat exchanger 902 was described as a heatexchanger like a plate heat exchanger that performs heat exchangebetween the refrigerant and the water circulating in the water circuit913. The heat exchanger 902 is not limited to such a heat exchanger butcan also be a heat exchanger that performs heat exchange between therefrigerant and air. The water circuit 913 can be a circuit in which adifferent fluid circulates instead of water.

While the heat exchanger 907 includes the first part 907 a and thesecond part 907 b in the above example, it is also possible to configurethe heat exchanger 902 to include two parts instead of or in addition tothe heat exchanger 907. In cases where the heat exchanger 902 performsheat exchange between the refrigerant and air, the heat exchanger 902can be configured so that each of the two parts includes a fan and thefans are respectively driven by driving force of separate motors.

While a configuration in which the heat exchanger 902 or 907 includestwo parts has been described as above, it is also possible to configurethe compressor 901 to include a first part (first compression mechanism)and a second part (second compression mechanism) instead of or inaddition to the heat exchanger 902 or 907. In this case, the compressor901 is controlled so that both of the first part and the second partperform the compression operation when the load on the heat pump device900 is relatively high and only one of the first part and the secondpart, e.g., only the first part, performs the compression operation whenthe load on the heat pump device 900 is relatively low.

In cases of employing such a configuration, the first part and thesecond part of the compressor 901 are respectively provided withseparate motors for driving them. For example, the first motor 41 andthe second motor 42 described in the first or second embodiment arerespectively used for driving the first part and the second part.

While a configuration in which at least one of the heat exchangers 902or 907 includes two parts and at least one of the heat exchangers 902 or907 is provided with two fans has been described as above, it is alsopossible to configure a heat exchanger to include three or more parts.In a generalized way, at least one of the heat exchangers 902 or 907 caninclude a plurality of parts and a fan may be provided corresponding toeach part. In such cases, driving a plurality of motors with oneinverter 4 is possible as described in the first or second embodiment.

Further, while a configuration in which the compressor 901 includes twoparts has been described, the compressor 901 may include three or moreparts. In a Generalized way, the compressor 901 can include a pluralityof parts and a motor may be provided corresponding to each part. In suchcases, driving a plurality of motors with one inverter 4 is possible asdescribed in the first or second embodiment.

The heat pump device 900 described in the third embodiment and the motordriving device 50 described in the first embodiment may be combinedtogether.

As described above, by employing the configuration described in thefirst or second embodiment when there are a plurality motors for drivingthe compressor 901 in the third embodiment or the fans of the heatexchanger 902 or 907, driving the plurality of motors by using oneinverter 4 becomes possible, and cost reduction, miniaturization andweight reduction of the heat pump device 900 and the refrigeration cycleapparatus 800 become possible.

In cases where the motors are those used for driving fans of a heatexchanger, the size of the heat exchanger can be increased thanks to theminiaturization of the motor driving device 50, and accordingly, theheat exchange efficiency increases further and efficiency improvement ofthe system also becomes possible.

Further, since it becomes possible to adjust the number of motors drivenby the inverter 4 by operating the open-close units (9, 9-1-9-4), it ispossible, for example, to operate only part of the plurality of motors,e.g., only the first motor 41, when the load is relatively low andoperate more motors, e.g., both of the first motor 41 and the secondmotor 42, when the load is relatively high, and changing the number ofdriven motors according to the load as above makes it possible toconsistently operate only a minimum necessary number of motors, by whichthe efficiency of the heat pump device can be increased further.

Furthermore, in cases where the control described in the first or secondembodiment is employed for the motors for driving the compressor 901,the danger of the step-out is eliminated, which makes it possible notonly to continue a stable compression operation but also to inhibitvibration due to the current pulsation, realizing not only noisereduction but also inhibition of breakage of components of the mainrefrigerant circuit 908 such as piping due to the vibration.

Moreover, in cases where the control described in the first or secondembodiment is employed for the motors for driving the fans of the heatexchanger 902 or 907, the danger of the step-out is eliminated, whichmakes it possible not only to continue a stable heat exchange operationand inhibit vibration due to the current pulsation but also to preventthe occurrence of a difference tone due to speed difference between thefans, and consequently, noise reduction is made possible.

Fourth Embodiment

In a refrigeration cycle apparatus (e.g., the refrigeration cycleapparatus 800 according to the third embodiment) formed of a combinationof the motor driving device 50 in the first embodiment and the heat pumpdevice 900 in the third embodiment, the operation mode of the heat pumpdevice 900 is switched corresponding to a change in the load on therefrigeration cycle apparatus, namely, the load on the heat pump device,the part performing the compression operation or the heat exchangeoperation in the compressor or the heat exchanger is switched accordingto the operation mode switching, and the number of motors driven ischanged correspondingly.

The switching of the part performing the heat exchange operation in theheat exchanger and the switching of the motor (s) for driving the fan(s)for blowing air to parts of the heat exchanger may have a small timedifference between each other as will be described below.

For example, let us assume here a configuration in which the heatexchanger includes n parts, n motors are provided corresponding to the nparts, the part performing the heat exchange operation among the n partsis switched according to the load on the refrigeration cycle apparatus,and each of the n motors is driven by the inverter 4 when thecorresponding part performs the heat exchange operation.

In this case, the driving of each of the n motors by the inverter may bestarted after the start of the heat exchange operation of the part ofthe heat exchanger corresponding to the motor. According to this method,the driving of each motor is started after the appearance of the effectof the heat pump action of the heat pump device, by which the powerconsumption by the motors can be reduced.

Conversely, it is also possible to start the driving of each of the nmotors by the inverter before the start of the heat exchange operationof the part of the heat exchanger corresponding to the motor. Accordingto this method, the driving of a motor has already been started when theeffect of the heat pump action of the heat pump device appears, whichenables effective use of the result of the heat pump action.

Further, the driving of each of the n motors by the inverter may bestopped after the stoppage of the heat exchange operation of the part ofthe heat exchanger corresponding to the motor. According to this method,effective use of the effect of the heat pump action becomes possible.

Conversely, it is also possible to stop the driving of each of the nmotors by the inverter before the stoppage of the heat exchangeoperation of the part of the heat exchanger corresponding to the motor.According to this method, the power consumption by the motors can bereduced.

Incidentally, the configurations shown in the above embodiments are justexamples or the configuration of the present invention; it is alsopossible to combine the above-described configurations with anotherpublicly known technology or to modify the configurations, like omittinga part, within a range not departing from the subject matter of thepresent invention.

What is claimed is:
 1. An outdoor unit for a refrigeration cycleapparatus, comprising: at least one heat exchanger; a first motorincluding a first rotor and a first fan, the first fan rotating togetherwith the first rotor; a second motor including a second rotor and asecond fan, the second fan rotating together with the second rotor; afirst lead wire electrically connected to the first motor; a second leadwire electrically connected to the second motor; an inverter thatapplies voltage to the first motor and the second motor through thefirst lead wire and the second lead wire respectively; a connectionswitching unit that is electrically connected to the second lead wireand switches the voltage applied to the second motor between on and off,the connection switching unit being formed of a wide band gapsemiconductor or an electromagnetic contactor; and a controller thatcontrols the inverter and the connection switching unit; and a housingcovering the first motor, the at least one heat exchanger, the inverter,the connection switching unit, and the controller and including anintake port and a discharge port, the intake port being vertically lowerthan the discharge port when the outdoor unit is in an installed state,wherein a path through which an air current generated by the first fanpasses extends from a vertically lower side to a vertically upper sidein the outdoor unit, the path extending from the vertically lower sideto the vertically upper side in the outdoor unit passes over theinverter and the at least one heat exchanger, the air current that haspassed over the inverter passes over the at least one heat exchanger,and the inverter is disposed closer to the first motor than to thesecond motor.
 2. The outdoor unit according to claim 1, wherein thecontroller is disposed closer to the first motor than to the secondmotor.
 3. The outdoor unit according to claim 1, further comprising acore that reduces noise current passing through the second lead wire,wherein the first lead wire is shorter than the second lead wire, andthe core is attached to the second lead wire.
 4. The outdoor unitaccording to claim 1, further comprising a core that reduces noisecurrent passing through the first lead wire and noise current passingthrough the second lead wire, wherein length of the first lead wire isequal to length of the second lead wire, current flowing through thefirst lead wire is in sync with current flowing through the second leadwire, and the core is attached to the first lead wire and the secondlead wire so that the current flowing through the first lead wire andthe current flowing through the second lead wire are in directionsopposite to each other in the core.
 5. The outdoor unit according toclaim 1, wherein the inverter is formed of at least one of asemiconductor switching element or a freewheeling diode.
 6. The outdoorunit according to claim 5, wherein the semiconductor switching elementis formed of a wide band gap semiconductor.
 7. The outdoor unitaccording to claim 5, wherein the freewheeling diode is formed of a wideband gap semiconductor.
 8. The outdoor unit according to claim 1,wherein the first motor includes a permanent magnet.
 9. The outdoor unitaccording to claim 1, wherein the second motor includes a permanentmagnet.
 10. A refrigeration cycle apparatus comprising the outdoor unitaccording to claim
 1. 11. The outdoor unit according to claim 1, whereinthe inverter is disposed under the first motor and the at least one heatexchanger.
 12. The outdoor unit according to claim 1, wherein thecontroller is disposed under the first motor and the at least one heatexchanger.
 13. The outdoor unit according to claim 1, wherein the pathpasses over the controller.